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Old 02-02-2013, 06:11 PM
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Originally Posted by 64nailhead View Post
I think it depends on what kind of highway cruising your doing. If your highway cruising is 70-75, then the 3.73 would be fine, but if your highway cruising is 55-65 then 4.10 would be better for mileage and driveability.

Here's what I found with your setup :
3.73 at 60 mph = 1800 rpms
4.10 at 60 mph = 2000 rpms

3.73 at 70 mph = 2100 rpms
4.10 at 70 mph = 2300 rpms

If fuel economy is the concern and cruising speeds are closer to 70, then the 3.73 are fine. Personally, though, the 4.10 will be more fun at all rpm ranges and shouldn't kill your fuel economy too much because your running relatively tall tires.

Now, if fuel economy isn't a concern, and your going to change the gears anyway, which you should, and you want it more snotty, then 4.56's would be even better yet and it would still be driveable at low speeds :
4.56 at 60 mph = 2200 rpms
4.56 at 70 mph = 2550 rpms

Just my opinion, for what its worth. Have fun.
I think to use fuel economy with a carbed 383 in the same sentence is a mistake.

Alot depends on which hat you want to wear.When you want a hot rod or when you want to have fuel economy.It's certainly a balancing point in parts choices.

What compounds this is 29.5 tires and O/D.

But to go to 4.56's or even 4.10's is I think a mistake.3.73's is a good around gear.Then to wire in switch to lock up or not T/C might be a better solution.Your trying for a cake and eat it too is something everyone wants.That is the main reason behind TCI's 6 speed auto and Gearvendor's spit O/D.Both very expensive and hard to justify on a return of investment giving the gas savings.

Guys talk about better gas mileage with these 383,but what exactly does that mean??.12 mpg vs 14 mpg??.383's are not known for gas mileage that have carbs.So the leads me to EFI systems.SFI's being a better choice.Certainly a EFI have a better spark curve and better fuel curve if tuned properly.Edelbrock with it's Pro-flow system is there again very expensive.

So which hat and when??. Hot rod or D.D'er. Get the TCI lock-out switch kit which is going to help you make that choice in conjunction with 3.73's.Make sure the cruise control is working.Right foot active control is going to directly effect the gas mileage. Start a research for a EFI system.
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